1. Field of the Invention
The present invention relates to a developer conveyance device configured to convey powdery developer and to an image forming device.
2. Description of the Related Art
In an image forming device using an electrophotographic method, for example, a surface of a photoreceptor (image carrier) is uniformly charged, the surface of the photoreceptor is scanned with a light beam, an electrostatic latent image is formed on the surface of the photoreceptor, the electrostatic latent image on the surface of the photoreceptor is developed by toner (developer), an toner image is formed on the surface of the photoreceptor, and the toner image is transferred from the surface of the photoreceptor to recording paper. Furthermore, immediately after the toner image has been transferred, the surface of the photoreceptor is cleaned by a cleaning device by removing the toner remaining on the surface of the photoreceptor, and the removed toner is conveyed to a container where it is recovered.
For example, in JP 2007-10921 A, a toner conveyance coil is arranged inside a toner recovery unit and a toner conveyance pipe and is rotated. Toner is conveyed from the toner recovery unit to the toner conveyance pipe by the toner conveyance coil, and the toner is discharged from a discharge opening at an end portion of the toner conveyance pipe. Furthermore, the toner conveyance coil is vibrated by being hooked to an interference member provided on an inner periphery of the toner conveyance pipe, such that the toner adhered to an inner wall of the toner conveyance pipe is shaken off.
In JP 2001-109343 A, a coil auger is arranged inside a pipe and is rotated. Toner is dropped on the coil auger through an opening at one end portion of the pipe, the toner is conveyed inside the pipe by the coil auger, and the toner is discharged to a waste toner recovery container from a discharge opening at the other end portion of the pipe.
Further, in JP 7-114301 A, a coil spring is arranged inside a toner conveyance path and is rotated in order to convey toner inside of the toner conveyance path. Solidification of the toner is prevented by changing a pitch and a diameter of the coil spring according to a position of the coil spring in a lengthwise direction, by providing another coil spring inside the coil spring and rotating two coil springs, or by inserting a shaft inside the coil spring and providing a projection on an outer periphery of the shaft.
In JP 2007-10921 A, the toner is naturally dropped on the toner conveyance coil through the toner recovery unit. However, since an upper side of the toner conveyance coil is opened in the toner recovery unit, when the toner conveyance coil is rotated, the toner easily moves in a vertical direction and passes through the toner conveyance coil, such that a toner conveyance performance when using the toner conveyance coil is decreased. Accordingly, when an amount of toner is large, the toner may be accumulated and solidified.
In JP 2001-109343 A as well, the toner is dropped on the coil auger through the opening at one end portion of the pipe. However, at the opening, since an upper side of the coil auger is opened, when the coil auger is rotated, the toner easily moves in the vertical direction and passes through the coil auger, such that a toner conveyance performance when using the coil auger is decreased. When the amount of toner is large, the toner may be accumulated and solidified.
Further, in JP 7-114301 A, the pitch and the diameter of the coil spring is changed. However, in a portion where the toner is naturally dropped, when the coil spring is rotated, the toner easily moves in the vertical direction and passes through the coil spring, such that a toner conveyance performance when using the coil spring is decreased. When the amount of the toner is large, it is considered that the toner is accumulated and solidified.
In JP 7-114301 A, another coil spring is provided inside the coil spring. However, in a portion where the toner is naturally dropped, the toner passes through two coil springs in the vertical direction, such that the toner hardly moves in a direction of conveyance. When the amount of the toner is large, it is considered that the toner is accumulated and solidified.
Further, in JP 7-114301 A, the projection is provided on the outer periphery of the shaft inside the coil spring. However, the shaft itself has no toner conveyance performance, such that in a portion where the toner is naturally dropped, the toner conveyance performance when using the coil spring becomes insufficient. When the amount of toner is large, it is considered that the toner is accumulated and solidified.
Further, in any of JP 2007-10921 A, JP 2001-109343 A, and JP 7-114301 A, when the solidification of the toner progresses, the toner conveyance coil, the coil auger, and the coil spring are elastically deformed being buried in the toner, such that the toner conveyance performance is decreased, and the solidification of the toner cannot be sufficiently prevented. It is not possible to solve this problem by providing another coil spring inside the coil spring as in JP 2001-109343 A or by providing a shaft inside the coil spring.